Blue thunbergia
  • Last updated:
  • 17 Apr 2022

Article by Rhea Phalan, Vector and Pest Plant Officer, Sunshine Coast Council

Blue thunbergia (Thunbergia grandiflora) really is a stunning vine and it’s no wonder gardeners grew it across the tropical world. Its beautiful purple flowers, dark green foliage, and the ability to grow well under tough conditions made it a perfect garden plant.

Under the Sunshine Coast Council Local Government Biosecurity Plan 2017 blue thunbergia however, is one of the highest priority invasive plants with the management response being eradication. As a Pest Plant Officer it’s never an easy job telling residents they need to get rid of plants like blue thunbergia. However, those who have had it growing on their property usually find that it starts to take over their garden and its vigorous growth is difficult to manage. When left unmanaged it can decimate corridors of native vegetation changing ecosystem values.

As part of Council’s biosecurity program blue thunbergia has been almost completely removed from five sites in Nambour, two properties in Witta, and properties in Buderim, Conondale, Rosemount, Woombye, Peachester, Glasshouse Mountains, Eerwah Vale, Montville, Flaxton as well as a property in Kiel Mountain. Blue thunbergia was found on this property in Kiel Mountain in 2018 and when council approached Michael, the owner of the property, he got to work straight away. Michael said ‘I have owned this piece of land for over 30 years. The infestation of thunbergia was slow and insidious, but in recent years I had noticed it smothering the trees and decided to control it’. Instead of just clearing the large patch of blue thunbergia he also cleared out understorey weeds like ochna (Ochna serrulata), asparagus fern (Asparagus aethiopicus cv. sprengeri) and golden trumpet tree (Handroanthus chrysotrichus).

By 2019 Michael had mostly eradicated the blue thunbergia and had started turning the area into (in his own words) ‘a forest garden, with an emphasis on flowering native shrubs’. Council would like to thank Michael and other residents for all the work they have done to manage invasive plants and increase the biodiversity on their properties.

For more information on blue thunbergia and control options please refer Biosecurity Queensland’s factsheet Blue thunbergia (daf.qld.gov.au) or contact Council for assistance.